Obstetric ultrasonography is the use of medical ultrasonography in pregnancyin which sound waves are used to create real-time visual images of the developing embryo or fetus in its mother's uterus womb. The procedure is a standard part of prenatal care in many countries, as it can provide a variety of information about the health of the mother, the timing and progress of the pregnancy, and the health and development of the embryo or fetus.
The International Society of Ultrasound in Obstetrics and Gynecology What is a us obstetric hookup scan recommends that pregnant women have routine obstetric ultrasounds between 18 weeks' and 22 weeks' gestational age the anatomy scan in order to confirm pregnancy timing, to measure the fetus so that growth abnormalities can be recognized quickly later in pregnancy, and to assess for congenital malformations and multiple pregnancies i.
Performing an ultrasound at this early stage of pregnancy can more accurately confirm the timing of the pregnancy and can also assess for multiple fetuses and major congenital abnormalities at an earlier stage.
There is no difference, however, in perinatal death or poor outcomes for babies. Below are useful terms on ultrasound: In normal state, each body tissue type, such as liver, spleen or kidney, has a unique echogenicity. Fortunately, gestational sac, yolk sac and embryo are surrounded by hyperechoic brighter body tissues. Traditional obstetric sonograms are done by placing a transducer on the abdomen of the pregnant woman.
One variant, a transvaginal sonography, is done with a probe placed in the woman's vagina. Transvaginal scans usually provide clearer pictures during early pregnancy and in obese women. Also used is Doppler sonography which detects the heartbeat of the fetus.
Doppler sonography can be used to evaluate the pulsations in the fetal heart and bloods vessels for signs of abnormalities.
Modern 3D ultrasound images provide greater detail for prenatal diagnosis than the older 2D ultrasound technology. A gestational sac can be reliably seen on transvaginal ultrasound by 5 weeks' gestational age approximately 3 weeks after ovulation. The embryo should be seen by the time the gestational sac measures 20 mm, about five-and-a-half weeks.
The heartbeat is usually seen on transvaginal ultrasound by the time the embryo measures 5 mm, but may not be visible until the embryo reaches 7 mm, around 7 weeks' gestational age. The rate of miscarriage, especially threatened miscarriage, drops significantly if normal heartbeat is detected. Contents in the cavity of the uterus seen at approximately 5 weeks of gestational age. Embryo at 5 weeks and 1 day of gestational age at top left with discernible heartbeat. In the first trimester, a standard ultrasound examination typically includes: In the second trimester, a standard ultrasound exam typically includes: Gestational age is usually determined by the date of the woman's last menstrual period, and assuming ovulation occurred on day fourteen of the menstrual cycle.
Sometimes a woman may be uncertain of the date of her last menstrual period, or there may be reason to suspect ovulation occurred significantly earlier or later than the fourteenth day of her cycle. Ultrasound scans offer an alternative method of estimating gestational age. The most accurate measurement for dating is the crown-rump length of the fetus, which can be done between 7 and 13 weeks of gestation.
After 13 weeks of gestation, the fetal age may be estimated using the biparietal diameter the "What is a us obstetric hookup scan" diameter of the head, across the two parietal bonesthe head circumference, the length of the femurthe crown-heel length head to heeland other fetal parameters.
Medical citation nedded Dating is more accurate when done earlier in the pregnancy; if a later scan gives a different estimate of gestational age, the estimated age is not normally changed but rather it is assumed the fetus is not growing at the expected rate.
Not useful for dating, the abdominal circumference of the fetus may also be measured. This gives an estimate of the weight and size of the fetus and is important when doing serial ultrasounds to monitor fetal growth. The sex the fetus may be discerned by ultrasound as early as 11 weeks' gestation. The accuracy is relatively imprecise when attempted early. The accuracy of fetal sex discernment depends on: Obstetric sonography has become useful in the assessment of the cervix in women at risk for premature birth.
A What is a us obstetric hookup scan cervix preterm is undesirable: In most countries, routine pregnancy sonographic scans are performed to detect developmental defects before birth.
This includes checking the status of the limbs and vital organs, as well as sometimes specific tests for abnormalities. Some abnormalities detected by ultrasound can be addressed by medical treatment in utero or by perinatal care, though indications of other abnormalities can lead to a decision regarding abortion. Perhaps the most common such test uses a measurement of the nuchal translucency thickness "NT-test", or " Nuchal Scan ". Ultrasound may also detect fetal organ anomaly.
Usually scans for this type of detection are done around 18 to 23 weeks of gestational age called the " anatomy scan ", "anomaly scan," or "level 2 ultrasound". Some resources indicate that there are clear reasons for this and that such scans are also clearly beneficial because ultrasound enables clear clinical advantages for assessing the developing fetus in terms of morphology, bone shape, skeletal features, fetal heart function, volume evaluation, fetal lung maturity,  and general fetus well being.
Second-trimester ultrasound screening for aneuploi- dies is based on looking for soft markers and some predefined structural abnormalities. Soft markers are variations from normal anatomy, which are more common in aneuploid fetuses compared to euploid ones. These markers are often not clinically significant and do not cause adverse pregnancy outcomes. Current evidence indicates that diagnostic ultrasound is safe for the unborn child, unlike radiographswhich employ ionizing radiation.